1. Field of the Invention
The present invention relates to surface-mount antennas used for mobile communication equipment and so forth, and in particular to communication apparatus using the surface-mount antennas.
2. Description of the Related Art
A .lambda./4 patch antenna as a conventional surface-mount antenna is shown in FIG. 7. A patch antenna 70 has a ground electrode 72 on one main surface of a board base member 71 comprising a dielectric, and a radiation electrode 73 on another main surface. The radiation electrode 73 is connected at one side to the ground electrode 72 on the main surface by a plurality of short pins 74. In addition, a feeding pin 75 is provided in the vicinity of the center of the radiation electrode 73.
In the patch antenna 70 having the above structure, when a high frequency signal is inputted to the radiation electrode 73 from the feeding pin 75, the radiation electrode 73 resonates as a resonator .lambda./4 long which has a grounded end at the short pins 74 and an open end at the opposed end, and functions as an antenna by radiating part of its resonant power into space. In addition, impedance matching is performed by providing the feeding pin 75 at the appropriate position between the grounded end and the open end.
However, according to the above patch antenna 70, the feeding pin 75 is difficult to provide since the feeding pin 75 is positioned in the vicinity of the center of the radiation electrode 73. In addition, reducing the size of the patch antenna 70 causes difficulty in matching due to the feeding pin 75 being close to the short pins 74, the inductance of the feeding pin 75, and changes in resonant frequency.